Network Management Strategies for the CIO
Kindly tell me that what are the advantages and disadvantages of wireless Ethernet bridge as
well as PRI
ISDN service. What should be the better choice for me to use?
These
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are two entirely different technologies, but I am guessing that you want to compare these as
alternatives for the "last mile" connection between your office and your Internet Service
Provider.
By wireless Ethernet, you probably mean 802.11 (2.4 and 5 GHz unlicensed wireless). Many Wireless ISPs (WISPs) use some form of 802.11 to support point-to-point bridging between customer locations and their point of presence (POP). Service characteristics vary greatly, depending upon factors like geography, line of site, tower locations, repeaters, and antennas. To illustrate, here are three examples in rural eastern Pennsylvania:
- ICDC Wireless - up to 15 miles, 6.2 Mbps
- Netconix - up to 5 miles, 9 Mbps
- WaveCrazy.Net - up to 4 miles, 2.5 Mbps
To find WISPs operating near your location, visit BroadbandReports.com and search for a wireless ISP by zip code. There are WISPs that string together several hops to create longer or higher-capacity links, so you really need to compare the characteristics of a specific wireless offering. But most services involve mounting a wireless bridge and antenna on the outside of your building (i.e., roof), aimed at the ISP's POP or nearest tower.
In comparison, ISDN PRI (Primary Rate Interface) characteristics are very consistent. Most telcos (ILECs or CLECs) offer ISDN data services over the same copper wires that deliver traditional analog phone services. An ISDN PRI is supported by a DS1 link, subdivided into 24 channels: 23 x 64 kbps B data or voice channels, plus one 64 kbps D channel for signaling. B channels can be bundled to carry up to 1.5 Mbps over cables that span any distance from your location to the nearest ISDN-capable telco switch (central office). Installers may use existing, unused telephone wires inside your building or may run new "inside wiring" for your ISDN PRI line. In addition to the ISDN link, you'll probably also want an ISDN Internet access account from your ISP. To get quotes from providers offering ISDN services to your location, use a website like USAccess or visit Dan Kegel's ISDN page.
Wireless links can be preferable in rural areas where there are no existing telco lines and open space makes line-of-site connections possible. In such cases, WISPs are often able to offer wireless "last mile" links for far less than a telco would charge you to install a new line. In metropolitan areas, ISDN may be more viable because telco wiring already exists, you may not have rooftop access, and there may be physical obstacles and frequency congestion that would impede wireless. Of course, which service is ACTUALLY most viable depends on your location and the services actually available to you there. When considering your wired options, note that DSL is often more economical these days than ISDN.
This was first published in December 2003
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